[1] Bu Ali Sina Univ, Fac Sci, Dept Math, Hamadan, Hamadan, Iran
[2] Univ Salento, Dipartimento Matemat & Fis E De Giorgi, Lecce, Italy
[3] China Three Gorges Univ, Dept Math, Yichang 443002, Hubei, Peoples R China
[4] Guangdong Univ Educ, Dept Math, Guangzhou 510303, Guangdong, Peoples R China
[5] North China Univ Water Resources & Elect Power, Sch Math & Stat, Zhengzhou 450046, Henan, Peoples R China
[6] East China JiaoTong Univ, Sch Sci, Nanchang 330013, Jiangxi, Peoples R China
[7] Guangdong Polytech Normal Univ, Dept Math, Guangzhou 510665, Guangdong, Peoples R China
[8] South China Univ Technol, Sch Math, Guangzhou 510640, Guangdong, Peoples R China
[9] Xuzhou Med Univ, Sch Med Informat & Engn, Xuzhou 221004, Jiangsu, Peoples R China